A lighting driving power supply (for example, a LED driving power supply) refers to a power converter that converts a power supply (for example, high voltage and industrial frequency AC i.e., mains, low voltage and high frequency AC such as the output of an electronic transformer, etc.) into specific voltage and current to drive a lighting apparatus or device to work (e.g. LED lighting), that is, to convert the power supply through a device such as a transformer to a rated power suitable for the operation of the lighting apparatus or device. At present, there are two ways to supply power to lighting apparatus or devices. One is to use a plurality of power supplies to separately power a plurality of lighting apparatus or devices. In this way, because each lighting apparatus or device has its own power supply, the combination method is flexible. Even if an apparatus or device fails, the operation of other apparatus or devices will not be affected. Therefore, the reliability and safety are high. However, due to the use of a plurality of power supplies and the need for supporting of related peripherals, the cost is higher. The other is to use one power supply to power one or more lighting apparatus or devices. Each lighting apparatus or device is connected in series or in parallel to the output circuit of the power supply that converts the voltage through the transformer. In this way, the cost is lower because only one power supply is used. However, this approach is less flexible. And when a plurality of lighting apparatus or devices are connected in series, once one of the lighting apparatus or devices fails, all lighting apparatus or devices will be affected and operational failures will occur. In practical applications, the above two ways to supply power can be used concurrently to achieve a balance between cost and performance. However, they do not fundamentally solve the problems existing in the current methods of lighting power supply.
A schematic diagram of the structure of a conventional lighting power supply control circuit applied to the above lighting power supply mode is shown in FIG. 1. The circuit includes a circuit (power supply control circuit) for controlling the power supply for the input power supply, a transformer, a rectifier circuit, a feedback circuit (FB), and an output circuit (such as a capacitor C1 and a resistor R1 connected in parallel in FIG. 1). The transformer includes a primary winding L0 and a secondary winding L1 coupled to each other. The rectifier circuit, the feedback circuit FB, and the output circuit (capacitor C1 and resistor R1) are connected in parallel across the loop of the secondary winding L1. The output of the feedback circuit FB is also connected to the power supply control circuit. The power supply control circuit only drives at the source of the power supply. It generally uses Pulse Width Modulation (PWM) to control the power supply. As described above, when a lighting power control circuit of this type is applied to lighting power supply, one or more lighting apparatus or devices (for example, one or more LED lights) can only be connected in series to the output of the loop of the secondary winding L1. If one of the lighting apparatus or devices fails, all lighting apparatus or devices will be affected and an operational failure will occur. This in turn means that the entire lighting power supply has hidden problems of reliability and safety.